Refrigerating apparatus



REFRIGERATING APPARATUS Filed Dec. 14, 1934 INVENTOR.

J'AcbB SM/MCK J/AM,Mz/2

ATTORNEY.

Patented Aug. 23, 1938 PATENT OFFICE BEFRIGERATING APPARATUS Jacob Smilack, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, at corporation of Delaware Application December 14, 1934, Serial No. 157,491

10 Claim.

maintaining a plurality of compartments at different temperatures.

Heretofore, in the construction of refrigerators of the compressor-condenser-expander type which have two or more evaporators maintained at different suction pressures for maintaining a plurality of compartments at difierent temperatures, it has been customary to utilize individual valves for controlling the flow of liquid refrigerant to each of the evaporators. Refrigerating systems having but a single evaporator have been constructed heretofore in which the use of a valve for controlling the refrigerant flow has been eliminated by the provision of a fixed restrictor. Before the present invention, however, the use of a fixed restrictor with its many obvious advantages over a float valve or expansion valve has been 20 limited to the so-called single temperature refrigerating systems.

It is an object of the present invention, therefore to provide a two-temperature or multiple evaporator refrigerating apparatus in which the 2., advantages inherent in a fixed restrictor are made available and in which the use of individual valves for controlling the rate of flow of refrigerant to the evaporators is made unnecessary.

A further object is to provide a novel restrictor for use in multiple refrigerating systems.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing:

The figure is a diagrammatic view of a refrigerating system embodying the present invention, portions of the mechanism being shown in cross section and on a larger scale.

Referring now to the drawing, there is illus trated a two-temperature refrigerating system comprising a compressor l0 driven by a motor I2 for delivering compressed refrigerant through a conduit i4 to a condenser Hi. The compressed refrigerant is liquefied in the condenser i8 and collected in a receiver l8, whence it is delivered by a conduit to a fixed restrictor 22. Liquid refrigerant is delivered from the restrictor 22 to a high temperature evaporator 24 and to a low temperature evaporator 26. The refrigerant expanded in the two evaporators is delivered by conduits 28, 38 and 32 to the compressor ill for recompression. The evaporators 24 and 26 may be disposed in separate compartments 58 and 80 respectively, in which it is desired to maintain relatively different temperatures. The general components of the refrigerating system thus de- 1 scribed may be of any well known construction,

it being understood that the illustration of these components is merely diagrammatic and representative of but one form which the elements. may conveniently take.

The restrictor 22 is of special construction com- 10 prising an inner cylindrical member 34 having a helical groove '36 formed upon its outer surface and an outer member 38 having a smooth inner surface. The outer member 38 is formed with an outlet connection 48 at its closed end, and 5 with a branch connection 42 intermediate its ends. The cylindrical members 34 and 38 are preferably assembled in a manner to provide a fluid tight flt between the adjacent surfaces of the two members. This may be done by giving 20 the members 34 and 38 an interference fit and telescoping them together while they are at widely different temperatures and permitting the temperatures of the members to equalize. After the members 34 and 38 have been thus assembled, a filter 44 is placed inside the hollow member 34 and a cap member 48 is secured to the open end of the outer cylindrical member 38. An inlet connection 48 is formed in the cap member 46. By this construction, there is provided a fixed restrictor having an inlet 48 at one end thereof, an outlet 40 at the opposite end, and a branch connection 42 intermediate its end. The helical groove 34 forms a conduit or passage of small cross section and great length through which refrigerant must .fiow from inlet 48 to the outlets and 42. It will be seen that the path of refrigerant from inlet 48 to outlet 42 is shorter than the path between inlet 48 and outlet 40, and that a portion of the two paths to the two 40 outlets is coincident.

Between the outlet 42 and the high temperature evaporator 24, there is interposed a suitable valve for controlling the flow of refrigerant to the high temperature evaporator 24. This may take the form of an electro-magnetically operated valve 50, of any suitable constructionby which the admission of liquid refrigerant to the high temperature evaporator may be started or stopped. In the form illustrated, the valve is so constructed so that when supplied with current, the passage from the outlet 42 to the evaporator 24 is maintained open and when the current supply is interrupted, the passage for refrigerant is maintained closed.v Preferably, this valve functions solely as an on-ofl control without varying the pressure of the liquid refrigerant while it is being delivered to the evaporator 24. Between the low temperature evaporator 26 and the conduit 2|, there is provided a suitable check valve 52 which acts to prevent the flow of expanded refrigerant from conduit 28 to the evaporator 2'.

Suitable control means are'pi'bvided for the motor l2 and for the valve 50 which may include a thermostatic or other temperature responsive switch 54 which is responsive to temperature conditions at the evaporator 24. Switch 54 is connected in circuit in series with the motor l2 and also with the electro-magnetic valve 50 so that whenever switch 54 is closed, the valve 50 will be opened and the motor l2 will run. A second thermostatic or other temperature responsive switch 56, is provided which is responsive to temperature conditions at the evaporator 25. The switch 56 is connected in parallel with that portion of the circuit including the switch 54 and the valve 50. Thus, whenever the switch 56 is closed, the motor l2 will be energized but the valve 50 will not be energized.

In operation, the high pressure liquefled refrigerant delivered through the conduit 2|! enters the restrictor 22 through the inlet 48 and is I'lltered by the filter element 44 before entering the helical groove 36 at the left hand end thereof. Assuming that refrigeration isv needed only in compartment 58, switch 54 will be closed and switch 56 will be open. Under these conditions, the motor I2 is running and thevalve 50 is open. Refrigerant passing through-the restrictor 22 will be delivered through the outlet 42. Inasmuch as the refrigerant passing to the outlet 42 transverses a shorter path than the refrigerant passing to the outlet 40, its pressure will be reduced less than that of the refrigerant leaving the outlet 40. Accordingly, a higher pressure will be maintained in the evaporator 24 than that maintained in the evaporator 26. Due to this higher pressure in evaporator 24, check valve 52 will be maintained closed so long as the pressure within the evaporator 28 is below that in evaporator 24. As soon as the temperature within the compartment 58 has been reduced to the point at which switch 54 opens, the valve 50 will close, thus cutting off the supply of liquid refrigerant to the evaporator 24 and stopping compressor i 0. When refrigeration is needed in compartment 60, switch 56 will close placing in operation the compressor which will act to reduce the pressure in the evaporator 24 and conduits 28, 30 and 32 until the point is reached where the check valve 52 will open, thus providing for w thdrawal of refrigerant from evaporator 26. Inasmuch as the liquid refrigerant passing through the restrictor to the outlet 40 transverses a longer path, its pressure will be reduced more than the reduction obtained in passing from the inlet 48 to the outlet 42 and the evaporator 26 will, therefore, operate at a lower suction pressure. As soon as the temperature within the compartment has been sufliciently reduced, the switch 56 will open, stopping operation of the compressor l0. Therefore, whenever either of the switches 54 or 56 closes, the compressor will be operated to withdraw refrigerant from the evaporator associated with the respective switch. It will be seen that when refrigeration is demanded in both compartments, the compartment 60 takes preference to the extent that its temperature is reduced to the cutoff point before the valve 50 isipermitted'to open.

While there has been illustrated'an embodiment of the invention utilizing two evaporators. it will be understood that three or more evaporators may be maintained at different tempera-- tures by similar apparatus utilizing a restrictor with two or more branch connections at different points along the length of the helical groove.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

-Whatis claimed is as follows:

1. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a restrictor having a passage of small cross-section and great length and having an inlet connected to said condenser at one end, a branch connection from said passage intermediate its ends to one of said evaporators, and another connection beyond said branch connection to the other of said evaporators.

2. A two-temperature refrigerating system comprising in combination a compressor, a condenser, a high temperature evaporator, a low temperature evaporator, a restrictor having a passage of small cross-section and great length therethrough for refrigerant, a branch connection communicating with said restrictor e intermediate its ends, and means including said branch connection for connecting said evaporators to said restrictor so that refrigerant flowing through the passage thereof from its one end to its other end is fed to the low temperature evaporator and refrigerant flowing through the passage of said restrictor to said branch connection is fed .to the high temperature evaporator.

3. A two-temperature refrigerating system comprising in combination a compressor, a condenser, a high temperature evaporator, a low temperature evaporator, a restrictor having a passage of small cross-section and great length therethrough for refrigerant and having an inlet at one end and an outlet at its other end, a branch connection communicating with said restrictor passage intermediate its ends and closer to the outlet end than the inlet end thereof, and means including said branch connection for connecting said evaporators to said restrictor so that refrigerant flowing through the passage thereof from its inlet end to its outlet end is fed to the low temperature evaporator and refrigerant flowing through the passage of said restrictor to said branch connection is fed to the high temperature evaporator.

4. A two-temperature refrigerating system comprising in combination a compressor, a condenser, a high temperature evaporator, a low temperature evaporator, a restrictor having a passage of small cross-section and great length therethrough for refrigerant, a branch connection communicating with said restrictor passage intermediate its ends, means including said branch connection for connecting said evaporators to said restrictor so that refrigerant flowing through the passage thereof from its one end to its other end is fed to the low temperature evaporator and refrigerant flowing through the passage of said resistor to said branch connection is fed to the high temperature evaporator, a valve for preventing back flow of gaseous refrigerant from the high temperature evaporator to the low temperature evaporator, and means for at times preventing the delivery of refrigerant 15 from the high temperature evaporator to the compressor.

5. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a resistor having a passage of small cross-section and great length and having an inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connection beyond said branch connection to the other of said evaporators, a valve in one of said connections, and means for actuating said valve in accordance with refrigeration conditions.

6. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a restrictor having a passage of small cross-section and great. length and having an inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connection beyond said branch connection to the other of said evaporators, a valve in said branch connection for controlling the flow of refrigerant to said other of said evaporators, and means for actuating said valve in accordance with refrigeration conditions of said other of said evaporators.

7. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a restrictor having a passage of small-cross-section and great length and having an inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connection beyond said branch connection to the other of said evaporators, a valve in one of said connections, compartments cooled by said evaporators, and controls responsive to conditions in said compartments for modifying the operation of said translating device.

8. A refrigerating system comprising in combination, a refrigerant translating device, a con.-

denser, a pair of evaporators, a restrictor having a passage of small cross-section and great length and having an inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connection beyond said branch connection to the other of said evaporators,-a valve in one of said connections, compartments cooled by said evaporators, and controls responsive to conditions in said compartments for modifying the operation of said translating device, one of said controls actuating said valve.

9. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a restrictor having a passage of small cross-section and great length and having an inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connectionbeyond said branch connection to the other .of said evaporators, a valve in one of said connections, compartments cooled by said evaporators, and thermostats in said compartments; controlling the flow of electricity to said translating device.

10. A refrigerating system comprising in combination, a refrigerant translating device, a condenser, a pair of evaporators, a restrictor having a passage of small cross-section andgreat length and having an'inlet at one end thereof connected to said condenser, a branch connection from said passage intermediate its ends to one of said evaporators, another connection beyond said branch connection to the other of said evaporators, a valve in one of said connections, compartments cooled by said evaporators, thermostats in said compartments controlling the flow of electricity to said translating device, a solenoid connected to said valve, and one of said thermostats controlling the flow of electricity to said 

